Dr. Cordain Responds to Critics of a Recent Paleo Diet Study

[Part One in our Series on Why the Paleo Diet is a Nutrient Dense Diet]

In April, news of a recent two-year study exploring the effects of a Paleo diet on postmenopausal women was presented at the 2016 Endocrine Society Annual Meeting. Soon afterwards, an hit the web detailing the positive results, but quickly shifted its focus to interviews with members of the nutrition community who focused more on their issues with the diet.

In this part 1 of our Nutrient Density Series Dr Cordain addresses these critiques and shows that when you just delve a little deeper into the science, the claim that the Paleo diet leads to nutrient deficiencies doesn’t hold scientific water…

Dr. Cordain’s Response:

(If you haven’t read it already, please check out the article at: )

The news of this recent study by Caroline Blomquist and colleagues at Umea University in Sweden presented at the Endocrine Society Annual (2016) Meeting, contributes to the growing body of literature demonstrating the therapeutic effect of contemporary Paleo Diets upon human health and well-being.1-21 It comes as no surprise to me that the Paleo Diet is incompletely understood by Connie Diekman, a registered dietician (RD) and Dr. Apovian, a nutritional scientist and M.D. who were asked to comment upon this study, because the concept itself is so new.

The fundamental idea underlying contemporary Paleo diets can be traced to Dr. Boyd Eaton’s seminal paper on the topic which appeared in the prestigious medical journal, The New England Journal of Medicine in 1985.22 Seventeen years later, I coined the term, “The Paleo Diet” with my first book of the same name in 2002.23 The first randomized controlled trial of contemporary “Paleo Diets” appeared 5 years later in 20071 by Staffan Lindeberg from the University of Lund in Sweden.

Today we have more than 20 clinical trials of Paleo Diets, including a recent meta-analysis of randomized controlled trials (RCT) which appeared in the American Journal of Clinical Nutrition in 201516 Hence, in the scientific literature, the concept of a “Paleo Diet” represents a brand new idea, only about 9 years old. 1-21

I do not fault Connie Diekman or Dr. Caroline Apovian for their comments about this study from Caroline Blomquist, because it is obvious that they are simply unfamiliar with the scientific literature regarding contemporary Paleo Diets. First, let me address the concerns of Connie Diekman, whom I quote below:

“Eliminating all dairy could put calcium, vitamin D and potassium intakes at risk, while cutting back on legumes and whole grains could cause deficiencies in fiber, manganese, magnesium and selenium, said Diekman. “Avoiding beans and grain foods also makes meeting nutrient needs harder.”

In regards to elimination of dairy, up to 70 % of the world’s adults are lactose intolerant and cannot digest unlimited quantities of milk.24 Accordingly, lactase non-persistence in adults represents the “wild-type” genotype in the world’s peoples24,25and no historically studied hunter gatherer society drinks milk, except for human milk, beyond the age of weaning.26,27 Increased consumption of milk

in contemporary populations significantly increases the risk of prostate cancer,28 perhaps ovarian cancer,29 and dairy consumption does not reduce the risk for bone fracture later in life.30-32

Adequate calcium metabolism is not just a function of calcium intake, but rather calcium balance (intake, absorption, loss). It is well established that at current adult calcium intakes (approximately700 mg/day), only 25 % of calcium is absorbed whereas 75 % is lost33 and with decreasing calcium intake, the relative absorption of calcium increases.33 Nutritional factors that increase calcium absorption (protein, vitamin D, vitamin C) and reduce calcium loss (net alkaline balance) play a greater role in calcium homeostasis than just the simple intake of calcium.34

In regards to milk and vitamin D, the elimination of milk from the diet will have little or no effect upon vitamin D metabolism because milk is such a poor dietary source of vitamin D. To even suggest that milk is a good source of vitamin D is a total stretch of the facts. The Institute of Medicine Daily’s recommended intake for vitamin D is 600 IU per day for most people.35 Although this advice represents a substantial increase from previous estimates, it still falls far short of human experimental evidence showing that ingestion of at least 2,000 IU of vitamin D per day is required to keep blood levels of vitamin D at the ideal concentration of 30 ng/ml.36-38

An eight oz. glass of raw milk (280 calories) straight from the cow without fortification gives you a paltry 3.6 IU of vitamin D. At this rate, you’d have to drink 167 eight oz. glasses of milk just to achieve the 600 IU daily recommendation. Because most of the milk we drink is fortified with vitamin D, an 8 oz. glass typically yields 100 IU of this nutrient. However, even with fortification, you would have to drink six 8 oz. glasses (1,680 calories or approximately 75% of your daily caloric intake) of milk to meet the daily requirement for vitamin D. If you wanted to reach the 2,000 IU level as suggested by the world’s best vitamin D researchers, you would have to drink 20 eight oz. glasses of fortified milk amounting to 5,600 calories. No one in their right mind would drink 20 glasses of milk a day, even if they could. Skim milk fortified with vitamin D will help, but why not just skip the milk and all of its attendant health problems and supplement your diet with vitamin D3, or better yet take in a little sunshine, as mother nature intended.

Okay, back to Connie Diekman’s position that elimination of dairy products could cause potassium deficiencies. The science just doesn’t back this. In contemporary Paleo Diets (potassium rich fruits and veggies typically comprise 30 to 45% of the daily caloric intake).26, 27, 39 Accordingly, nutritional analyses of contemporary Paleo diets show the potassium content (9,062 mg) of example diets to be nearly 3.5 times greater than average values (2,620 mg) for potassium in the U.S. diet.39

[In part 3 of this series we put a one-day Paleo menu up against two popular western diets and show the far greater potassium content of a Paleo menu – without any dairy.]

Ms. Diekman goes on to state that “while cutting back on legumes and whole grains could cause deficiencies in fiber, manganese, magnesium and selenium, avoiding beans and grain foods also makes meeting nutrient needs harder.”

In reality, the elimination of whole or refined grains and beans actually increases the nutrient density of the 12 most common vitamin and mineral insufficiencies in the U.S. diet.27,39 See Appendix A below for more detail. The reason for this phenomenon is that the overall trace nutrient density of whole grains and legumes is considerably lower than for an equivalent caloric amount of fresh seafood, fresh vegetables, fresh fruits and grass produced lean meats, as the Appendix shows.27,29

Further, both beans and whole grains contain high concentrations of phytate which significantly impair the absorption of these foods’ minerals including calcium, zinc, magnesium, iron, selenium and manganese.40-49

Because the Paleo Diet encourages elimination or reduction of processed foods, it further increases dietary fiber. The fiber content (42.5 g) of example Paleo Diets39 is considerably higher than values in the U.S. diet (15.1 g) and even higher than recommended values (25-30 g). Soluble fibers modestly reduce LDL and total cholesterol concentrations, and fiber by slowing gastric emptying may reduce appetite and help to control caloric intake.50

A final point brought up by Ms. Diekman is worth examining: “while cutting back on legumes and whole grains could cause deficiencies in fiber, manganese, magnesium and selenium.”. Actually as Appendix A reveals, staple food components in contemporary Paleo Diets are rich sources of magnesium. 100 kcal averaged portions of 20 commonplace vegetables provide the highest dietary source of magnesium at 54.5 mg; seafood yields 36.1 mg of magnesium per 100 kcal, nuts and seeds deliver 35.8 mg per 100 kcal and fruits supply 24.6 mg of magnesium per 100 kcal. Contrast these figures to the magnesium content of legumes (43.7 mg per 100 kcal) and whole grains (29.1 mg per 100 kcal). However impressive these figures may appear at first, in our bodies (in vivo), these values are significantly reduced because of the phytate found in legumes and whole grains which impairs absorption of magnesium.44, 49 Accordingly, the elimination of legumes and beans in contemporary Paleo Diets actually increases the usable and functional magnesium content of the diet. Nutrient analyses of Paleo diets show them to contain a whopping 691 mg/day of magnesiun39 compared to its DRI (400 mg/day).

A similar situation exists for selenium and manganese. Absorption of both minerals in legumes and whole grains is significantly impaired during digestion because of the high phytate content of these foods.40, 42, 43, 46 Appendix A reveals that the four highest dietary sources of selenium come from foods consumed almost every day in contemporary Paleo diets: [1] seafoods (39.7 μg), [2] nuts and seeds (31.1 μg), [3] eggs (19.9 μg) and [4] lean meats (13.8 μg). In contrast legumes (2.3 μg) and whole grains (6.2 μg) contain some of the lowest dietary concentrations of selenium.

For manganese, the highest dietary source of this mineral comes from foods that are consumed daily in contemporary Paleo diets: non-starchy vegetables (0.60 mg). Once again, in Appendix A, whole grains (0.57 mg) and legumes (0.53 mg) appear to maintain impressive concentrations of manganese, but in vivo, these values are severely reduced by phytate present in these foods.43 Besides non-starchy vegetables, other Paleo diet foods are good sources of manganese including nuts and seeds (0.49 mg) and fresh fruits (0.24 mg).

In conclusion, it is simply untrue to suggest that contemporary Paleo diets could cause deficiencies in fiber, magnesium, manganese and selenium. Actually, contemporary Paleo diets provide the consumer with quantities of these nutrients that easily meet or surpass governmental DRI recommendations as Appendix A demonstrates.39

In regards to Dr. Apovian’s comments: “You’re basically eliminating all processed and simple carbohydrates, which we know is one of the exacerbations or causes of overweight, obesity and insulin resistance.”

Yes, I am in complete agreement that elimination of all processed foods and simple carbohydrates would effectively eradicate or greatly reduce the causes of overweight, obesity and insulin resistance in western populations. Such a simple scientific solution should become part of our national health policy, yet the nutritional community is apparently not ready to accept such a fundamental position acknowledged by Dr. Apovian and consistent with Paleo diet nutritional principles. Dieticians and nutritional scientists should know that these suggestions are some of the best they can make to prevent overweight and obesity in their clients. We suggest the 85:15 rule in which people follow Paleo 85 % of the time and 15 % of the time (and energy) they may stray from Paleo guidelines, yet achieve real improvements in health and wellbeing.1-21

Dr. Apovian, director of the Nutrition and Weight Management Center at Boston Medical Center, goes on to say, “I’m not sure I would say this is a Paleo diet. This is more of a cross between a Paleo diet and a Mediterranean diet.”

Hmm! I’m not sure how or why Dr. Apovian’s comment arose, but as one of the founders of the Paleo diet, and the scientist who coined the term, “The Paleo Diet”, I can say that the two diets have little in common. Figure 1 below represents a characteristic Mediterranean diet and how it differs from a representative Paleo Diet.

Perhaps, the most glaring difference between the two diets is that the Mediterranean diet includes daily portions of high glycemic load carbohydrates such as bread, pasta, rice and potatoes. The Mediterranean diet also varies from the Paleo diet in that beans and legumes represent daily dietary staples, as are dairy foods. Highly salted foods such as cheese and olives are permitted on the Mediterranean diet whereas consumption of salt and salted foods are discouraged on the Paleo Diet. Finally, consumption of fresh meat is not regularly eaten in Mediterranean diets, whereas no such prohibition is made on fresh, grass produced meats (poultry, pork, beef, lamb, game meat, organ meats, etc.) with contemporary Paleo diets.

Perhaps, the two diets are loosely similar in that both diets recommend consumption of fish, poultry, eggs, plenty of fresh fruits and vegetables and olive oil.

Figure 1. How the Typical Mediterranean Diet varies from the Paleo Diet.

Let me now respond to Dr. Apovian’s perceptions on the cost of contemporary Paleo diets: “To the average American and to the lower socioeconomic classes that suffer the most from disease and obesity, they can’t do this. It’s financially impossible. Low-income people who need to eat like this, can’t. That’s the problem in this country.”

Dr Apovian has a great deal of experience working with different socioeconomic classes, however there is research showing that a Paleo diet is financially feasible.51 Many low-income consumers face a limited budget for food purchases. The United States Department of Agriculture (USDA) has developed the “Thrifty Food Plan” to address the problem of consuming a healthy diet given a budget constraint. This dietary optimization program uses common food choices to build a suitable diet.

A recent paper used the USDA Thrifty Food Plan data sets to test the feasibility of consuming a contemporary Paleo diet given a limited budget.51 Constraints were applied to the diet optimization model to restrict grains, dairy, and certain other food categories. Constraints were also applied for macronutrients, micronutrients, and long-chain polyunsaturated fatty acids.To quote the authors of this study: “the results show that it is possible to consume a Paleolithic diet given the constraints”.51 The Paleo diet clearly is within the reach of “the average American” and even within the reach of virtually all low income consumers with only a 9.3% increase in expenditure for food.51

***We welcome input to this article from lead study author Caroline Blomquist, a doctoral student at Umea University in Sweden and from the two experts, Dr. Caroline Apovian director of the Nutrition and Weight Management Center at Boston Medical Center (who was kind enough to do an interview with our team and is the focus of ourpart 2 on Nutrient Density,) and Connie Diekman, M.Ed., RD, director, University Nutrition, Washington University in St. Louis, and former president, Academy of Nutrition and Dietetics, who critiqued the original scientific study by lead author Caroline Blomquist who presented the study at the Endocrine Society’s Annual Meeting in Boston on April 2, 2016.

Appendix A

The Nutrient Density for the 12 Vitamins and Minerals Most Lacking in the U.S. Diet by Food Groups. Note Appendix A is attached as a downloadable PDFwith this blog. Also note that in Part 3 of our series on Nutrient Density, we address this table directly and how it shows that a Paleo diet is a more nutrient dense diet.

Key and Notes for Appendix A. All micronutrient (vitamin and mineral) data was derived from the USDA Standard Reference Database via the nutritional software, Nutritionist Pro.52 DRI values were obtained from The National Academies, Dietary Reference Intakes.53 When DRI values differed between genders, the highest value for 19-30-year-old adults was used to calculate % DRI for each micronutrient. All foods were separated into one of ten specific categories (whole grains, milk, fresh fruits, fresh non-starchy vegetables, fresh fish and seafood, fresh lean meats, nuts and seeds, legumes and beans, starchy root vegetables and eggs). Foods listed for each category represented the most frequently commonly consumed items in the U.S. diet. Values for individual micronutrients represent mean 100 kcal value for the entire category of foods. For instance, the zinc value (6.09 mg) for whole grains represents the average (mean) 100 kcal value for all whole grains (barley, corn, millet, oats, rice, rye, sorghum and wheat). The % DRI values were calculated by dividing the actual value; for example, zinc (0.67 mg) by the DRI (11 mg) for zinc times 100 = % DRI (6.09 %). All food category % DRI values were summed to obtain interval level data in order to compare the sum total micronutrient density for any food category. The most nutrient dense food categories in rank order are: [#1] seafood (sum score: 459.6), [#2] fresh vegetables (sum score: 378), [#3] fruits (sum score: 152.7), [#4] lean meats (sum score: 135.9), [#5] legumes (sum score: 99.9), [#6] eggs (sum score: 98.7), [#7] starchy roots (sum score: 95.6), [#8] whole milk (sum score: 94.3), [#9] whole grains (sum score: 49.5), [#10 nuts and seeds (sum score: 45.8). Micronutrient values for all food categories were also calculated for selenium and manganese but were not included in the sum total evaluation of each food category, as the percentage of the population lacking in these two micronutrients is not available.

Table 1. Mean nutrient density of the major food groups. Table created by Loren Cordain, Ph.D. using Nutritionist Pro Software. Nutrient content of each food item was determined based on a 100 kcal sample. Percent of Dietary Reference Intake (DRI) values were summed to determine overall nutrient density of each group. Food groups are ranked from left to right based on their density. Food groups considered a healthy part of a Paleo diet are highlighted in green. Food groups that are not considered part of a Paleo diet are highlighted in red. *Click Here To Download PDF of Table

Dr. Loren Cordain is Professor Emeritus of the Department of Health and Exercise Science at Colorado State University in Fort Collins, Colorado. His research emphasis over the past 20 years has focused upon the evolutionary and anthropological basis for diet, health and well being in modern humans. Dr. Cordain’s scientific publications have examined the nutritional characteristics of worldwide hunter-gatherer diets as well as the nutrient composition of wild plant and animal foods consumed by foraging humans. He is the world’s leading expert on Paleolithic diets and has lectured extensively on the Paleolithic nutrition worldwide. Dr. Cordain is the author of six popular bestselling books including The Real Paleo Diet Cookbook, The Paleo Diet, The Paleo Answer, and The Paleo Diet Cookbook, summarizing his research findings.

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“4” Comments

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I am shocked that dieticians and nutritionalists scoff at this diet. I started the diet 5 years ago using urban gardening techniques to grow my veggies and herbs considering my impoverished income. It has been a life saver, especially since my heart attack. My cardiologist advises this plan as the best for the human body and tons of research and historical evidence prove that. Some people in healthcare just don’t want to accept what’s in their face.

Thanks Dr Cordain again for a timely restatement of the benefits of a properly constituted Paleo Diet.
I too have been following Boyd Eaton over the past few decades, both personally and professionally as a medical health adviser, and Dr Cordain and his collarborators have done a sterling job in publicising and developing Eaton’s views so as to make a true Paleo Diet practical and affordable.
If only the commercial shysters who call themselves Paleo would take heed – unfortunately there are too many purveyors of high sodium high saturated fat low vegie high processed and commercial supplement food type diets clogging the internet.
I have also costed out Paleo eating in Australia, and I agree it is totally affordable!
So a big thank you to Dr Cordain, whom I can thank both for my own great personal health as well as for providing professional advice for me to pass on to my clients

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